167 



CLVI. POLYGONE.E. The Buck-wheat Tribe. 



Polyoonm, Juss. Gen. 82. (1789); R. Brown, Prodr. 418. (1810) ; Lindl. Synops.209. (1829.) 



Diagnosis. Apetalous dicotyledons, with definite erect ovula, ochreate sti- 

 pulae, and a radicle remote from the hilum. 

 Anomalies. Eriogonum has not ochreate stipulse. 



Essential Chahacteh. — Calyx divided, inferior, imbricated in {estivation. Stamens defi- 

 nite, inserted in the bottom of the calyx ; anthers dehiscing 1 lengthwise. Ovarium superior, 

 with a single erect ovulum ; styles or stigmas several. Nut usually triangular, naked, or pro- 

 tected by the calyx. Seed with farinaceous albumen, rarely with scarcely any ; embryo in- 

 verted, generally on one side; plumula inconspicuous; radicle at the end remote from the 

 hilum. — Herbaceous plants, rarely shrubs. Leaves alternate, their stipule cohering round the 

 stem in the form of an ochrea j when young, rolled backwards. Flowers occasionally dicli- 

 nous, often in racemes. 



Affinities. Mr. Brown remarks, that " the erect ovulum with a superior 

 radicle together afford the most important mark of distinction between Polygo- 

 neae and Chenopodes, a character which obtains even in the genus Eriogonum, 

 in which there is no petiolar sheath, and scarcely any albumen, the little that 

 exists being fleshy." Generally speaking, however, the cohesion of the sca- 

 rious stipulae into a sheath, technically called an ochrea, or boot, is sufficient to 

 distinguish Polygonese from all other plants. For their relation to Begonia- 

 ceffi, see that order. 



Geography. There are few parts of the world that do not acknowledge the 

 presence of plants of this order. In Europe, Africa, North America, and 

 Asia, they fill the ditches, hedges, and waste grounds, in the form of Docks 

 and Persicarias ; the fields, mountains, and heaths, as Sorrels and trailing or 

 twining Polygonums ; in South America and the West Indies they take the 

 form of Coccolobas or sea-side grapes ; in the Levant, of Rhubarbs ; and even 

 in the desolate regions of the North Pole they are found in the shape of Oxyria, 



Properties. Sorrel on the one hand, and Rhubarb on the other, may be 

 taken as the representatives of the general qualities of this order. While the 

 leaves and young shoots are acid and agreeable, the roots are universally nau- 

 seous and purgative. To these two qualities is to be superadded a third, that of 

 astringency, which is found in a greater or less degree in the whole order, but 

 which becomes in Coccoloba uvifera so powerful as to rival Gum Kino in its 

 . effects. Some of the Polygonums are extremely acrid, as the P. Hydropiper, 

 which is said to blister the skin. There is a species of Polygonum, called Ca- 

 tayain the language of the Brazilian Indians, an infusion of the ashes of which 

 is used to purify and condense the juice of the sugar-cane. It has a very bit- 

 ter peppery taste, and is employed on the Rio St. Francisco with advantage in 

 the disease called O Largo, which is an enlargement of the colon, caused by 

 debility. Pr. Max. Trav. 71. The stem of the Rheum has been supposed # to 

 contain a peculiar acid called the rheumic, but this is now known to be the ox- 

 alic. Turner, 641. Rumex acetosa contains pure oxalic acid. Ibid. 623. 

 The principle in which the active property of Rhubarb exists is supposed to be 

 a peculiar chemical substance called Rhubarbarin. Ibid. 701. Some infor- 

 mation may be found upon the Rhubarbs of India in the Trans, of the Med. 

 and Phys. Soc. of Calcutta, 3. 438. by Dr. Royle ; but nothing certain had been 

 collected by him with regard to the plant producing the true officinal substance. 

 Many species of Polygonum are used in dyeing. The seeds of P. fagopyrum 

 and tartaricum are used as food, for the sake of their mealy albumen ; those of 

 P. aviculare are said to be powerfully emetic and purgative ; but this is doubted 

 by Meisner. Mon, 49. The seeda of Polygonum barbatum are used as me- 



